The present invention relates to the art of earth boring and, more particularly, to a rotary rock bit suitable for drilling in extremely hard formations, such as hard taconite where the usual multiple-purpose bit encounters problems because of the character of the extremely hard high-strength rock.
The rapidly increasing demand for the earth's natural resources such as oil and gas and various types of ores extracted by the mining industry has created the need for improved drilling bits. The present invention provides a drilling bit for drilling in extremely hard formations, such as are encountered in deep oil and gas wells and in drilling in hard ore-bearing formations such as the iron bearing taconite formations.
A more specific example of the need for the bit of the present invention will be described with reference to bits for use in applications for drilling blast holes such as those commonly encountered in mining areas where the holes are usually of relatively shallow depth. Current state of the art blast hole bits in use around the world perform satisfactorily in medium-hard to hard formations, but when extremely hard, high-strength formations are encountered, the bits suffer extreme battering of the cutting structure components in abnormally short rotating hours.